Method of treating impure lead and lead alloys



Patented Dec. 4, 1928..

NET STATES ATNT @FFHCE.

GEORGE E. DALIBEY, OF EAST BERLIN. AND THOMAS P. HANFORD, 0F BERLIN, CON- NECTICUT, ASSIGNORS TO THESTANLEY CHEMICAL COMPANY, OF EAST BERLIN. CONNECTICUT, A CORPORATION OF CONNECTICUT.

IV'ETHOD OF TREATING HlLEPURE LEAD AND LEAD ALLOYS.

No Drawing.

This invention relates to a method of treating impure lead and lead alloys.

More partit ularly the invention relates to a method of removing metallic impurities such, for example, as tin and antimony. These metals also exist in lead alloys and it is to be understood that the term impure lead is intended to include lead alloys.

It an object of the present invention to provide an economical method of treating impure lead to remove the impurities referred to so as to reclaim connnercially valuable products.

With this 'encral object in view, the invention consists in the method which is hereinat'ter described and then more particularly pointed out in the claim.

In carrying out the method of the invention, any given metallic impurity combined with the lead is removed by causing the impurity to replace the metal contained in the acid radical in a salt having an alkali metal as a base. That is. the impure lead is treated with an alkali salt of a metal which, by reason of preferential chemical atlinity, is capable of being reduced to a metallic state by one or more of he metallic impurities, whereby the reduced metal is replaced in the alkali compound by the impurity or impurities to be removed.

For convenience of description sodium compounds are used as an example of the alkali salts referred to and the particular salt used depends on the metallic impurity to be removed. For example, for an impure lead in which the impurity to be removed is antimony. the salt used is sodium plmnbate or plumbite. In this case the reaction causes the lead of the sodium plumbate to be red need to metallic lead. the antimony replacing it in the sodium compound to form sodium antimonate. Similarly. when tin is the impurity to be removed, the salt used is sodium antimonate or antimonite. In this case the antimony ot' the salt is reduced to metallic antimony and the tin replaces it in the sodium compound, forming sodium stannate.

The reactions described may be properly carried out under various conditions. For example, linely divided particles of lead having antimony as an impurity may be brought into contact with a Water solution of sodium plumbate or sodium plumbitc. Eventually the lead of the sodium salt is reduced to metallic lead and the antimony re- Serial No. 161,237.

places the laid in the sodium compound, forming sodium antimonate. Similarly impure lead having tin as its impurity may be brought into contact with a water solution oi sodium antimonate or antimonite.

As a result of the reactions referred to the metallic lead or antimony is precipitated as a sludge which may be separated by mechanical means and further treated as desired. There remains a solution containing one or more sodium salts. This solution may be further treated to reclaim valuable products, for example, by the method disclosed in a copending application tiled of even date herewith, Serial No. 161,236.

If desirechthc impure lead may be treated in a molten condition. In this case. the sodium-metallic salt or salts used may be brought into contacts with the molten impure lead through the medium of fused caustic soda. Upon the reactions above described, there results a molten alloy and one or more sodium salts. Both products may be further treated for the reclamation of values. The molten alloy may be treated. for example,v in accordance with the method disclosed in our copending application filed May 4t. 1926, Serial No. 108,726. The salts may be treated, for example, according to the method disclosed in application Serial No. 161,238 above referred to.

While tin and antimony have been referred to as metals to be removed from impure lead. it is to be understood that other metals found in impure lead may he removed according; to the present invention. The replacements of the metals in a sodium-metallic salt by metals in the impure lead talce place in accordance with the preferential chemical affinity for the position ol' the element forming acid radical of the alkali salt.

\Vhat is claimed is:

The method of recovering valuahle products from impure lead containing tin and ant imony, which con'iprises treating the impure lead with a sodium-antimony salt and cansing the antimony in said salt to be reduced to metallic antimony and the tin in the impure lead to replace the antimony in said salt, forming sodium stannate.

In testimony whereof, we have hereunto set our hands.

GEORGE E. DALBEY. THOMAS P. HANFORD.

EER'NFHCATE OF MURREMIQN.

Patent No. 1,693,639. Granted Deoernher 4, 1928. to

GEORGE E. DALBEY 'h'ii AL.

it is hereby certified that error appears in the printed specification oi the above numbered patent requiring correct ion as ioiiows: Page i, iine 70, for number "161,236" read "161,238"; and that the said Letters Patent should he read with this correction therein that the same may conform m the record of the ease in the Patent Office.

Signed and sealed this 15th day of January, A. D. 192).

M. 3. Moore, (Seal) 4 Acting Commissioner of Patents- 

